1. Field of the Invention
The present disclosure relates to seals, and more particularly to seals for turbomachinery, such as for example seals between a case and rotor turbine blades in a gas turbine engine.
2. Description of Related Art
Leakage of flow-path air may occur in turbomachinery between the tips of a rotating blade structure and the outer static structure. This leakage has a negative effect on performance, efficiency, fuel burn, and component life. Turbomachinery with a wide operating range, such as an aircraft gas turbine engine, conventionally requires large tip clearances due to the mismatch in thermal responses between the rotating structure and the static structure. A static structure with a rapid thermal response rate will experience significant closure to the rotating structure during rapid decelerations. Conversely, a static structure with a slow thermal response will experience significant closure to the rotating structure during rapid accelerations. As a result, both configurations require large tip clearances throughout the operating range. In particular, sudden excursions during aircraft missions drive the need for larger tip clearances at idle, take off, and cruise.